1. Field of the Invention
The present invention relates to a method for generating a detonation pressure wherein a high shock pressure appropriate for pressure joining and pressure forming of materials can be easily obtained and an apparatus therefor.
2. Description of the Related Art
Methods for joining or forming plates and for processing food under pressure by generating a high shock pressure have been proposed.
A known apparatus for joining materials under a shock pressure is described as follows:
In the known apparatus, a base material is placed on a holding means such as a surface plate or the like, and a material to be joined to the base material under pressure is held in parallel or at some angle relative to the base material, explosives and cushioning materials are disposed on the entire surface of the material to be joined, and the explosives on the material are exploded from an end of the explosives to the other end thereof. Each of the parts of the material to be joined one after another strike the base material from an end of the material to the other end thereof as the explosion goes. When the material to be joined strikes the base material during the explosion, oxide films are blown away. The material to be joined is deposited on the base material by heat generated by plastic deformation of the material to be joined and the base material. At the same time, the material to be joined is pressed and joined to the base material by a shock pressure of the explosion.
In this known apparatus, however, there are problems such as 1 use of dangerous and expensive explosives, 2 limitation of places where the apparatus can be used due to danger where the explosives are placed, 3 difficulties in control of pressures applied to materials and 4 no applicability of the apparatus to a short-time repeated joining of materials.
The following apparatuses are known for forming a plate under an underwater shock pressure.
Japanese Patent Application Laid Open No. 157725/89 discloses an underwater shock pressure generating apparatus wherein an impact hydraulic pressure is generated in liquid by shooting a bullet into the liquid such as pressure water, applying the pressure to a material and pressing the material to a die, thereby carrying out a three-dimensional forming of the material.
Further, an explosion forming apparatus is known wherein a three-dimensional forming of a thin plate is carried out by generating an underwater shock pressure by combusting explosives under water and utilizing the underwater shock pressure. This apparatus is used mainly for forming of large size parts.
Furthermore, an apparatus is known wherein an underwater shock pressure is generated by causing a piston accelerated by a gas pressure to a high speed to strike the surface of a pressure liquid contained in a vessel and a member to be formed is pressed to a die by the underwater shock pressure. This apparatus is used for forming comparatively small size parts.
In the above-mentioned apparatuses, however, there are problems such as 1 use of dangerous and expensive explosives, 2 limitation of places where the apparatus can be used due to danger where the explosives are placed, 3 difficulties in control of pressures applied to materials and 4 no applicability of the apparatus to a short-time repeated joining of materials.
It is also known that application of a high pressure to foods is effective in keeping the foods in a good state during processing of the foods. For example, meat after slaughter becomes rigid if it is left as it is. This is because muscle fibrils become stiff. To prevent muscle fibrils from stiffening, a method for softening meat by breaking the muscle fibrils by applying a static superhigh pressure to the muscle fibrils for 5 to 10 minutes on the occasion of freezing meat for preservation is adopted. Beverages or food containing a great amount of liquid are sterilized by applying a superhigh pressure to the beverage or the food. A cold isostatic pressing method is typical of methods for obtaining the above static superhigh pressure.
Applying a static superhigh pressure to food for a long time causes a taste of the food to change, which is undesirable.
Moreover, it is pointed out that a high cost is required for applying a static superhigh pressure to food, and it is difficult to treat a large amount of food for a short time.